physics

• Particle groups


  • Hadrons
  • Leptons
• Leptons


  Fundamental particles including electron, muon (heavy electron), and neutrino
• Lepton number


  Leptons have a lepton number of 1, their antiparticles have a lepton number of -1
• Neutrinos


  Can be electron neutrinos or muon neutrinos, their lepton numbers must be treated separately
• Quark flavours


  • Up
  • Down
  • Strange
• Strangeness


  Strange quarks have strangeness -1, antistrange quarks have strangeness +1
• Baryon number


  Baryons have a baryon number of +1 or -1 if they contain antiquarks
• Neutrons are up-down-down, protons are up-up-down
• Electromagnetic force

  Affects any charged particle, exchange particle is the photon
• Particle groups


  • Hadrons
  • Leptons
• Leptons


  Fundamental particles including electron, muon (heavy electron), and neutrino
• Lepton number


  Leptons have a lepton number of 1, their antiparticles have a lepton number of -1
• Types of neutrinos


  • Electron neutrinos
  • Muon neutrinos
• Quark flavours


  • Up
  • Down
  • Strange
• Strangeness


  Strange quarks have strangeness -1, antistrange quarks have strangeness +1
• Baryon number


  Baryons have a baryon number of +1 or -1 depending on presence of antiquarks
• Electromagnetic force


  Affects any charged particle, exchange particle is the photon
• Gravity


  Exchange particle is the graviton
• Weak force


  Affects any particle, exchange particles are W+, W-, Z0 bosons
• Strong force


  Affects hadrons only, exchange particle is the gluon
• Electrostatic repulsion between protons


  Pushes outwards
• Strong force


  Pulls inwards
• When the forces are balanced, a nucleus is stable
• Range of strong force

  1. 4 fm, switches from attractive to repulsive at 0.5 fm
• In any interaction, charge, baryon number and lepton numbers must be conserved
• Beta minus decay


  Down quark in neutron decays to up quark, emitting electron and antineutrino
• Feynman diagrams


  Used to represent weak interactions involving W+ or W- bosons
• Interactions involving leptons must be weak, regardless of strangeness
• Interactions involving only hadrons and conserving strangeness must be strong
• Interactions involving hadrons and not conserving strangeness must be weak
• Specific charge


  Charge to mass ratio of a particle, unit is C/kg
• Types of radiation


  • Electromagnetic (emitted by electrons)
  • Gamma (emitted by nucleus)
  • Alpha (emitted in radioactive decay)
  • Beta (emitted in radioactive decay)
• Gamma radiation can ionize atoms and cause cell/DNA damage
• Alpha decay


  1. Nucleus emits alpha particle (2 protons, 2 neutrons)

  2. Daughter nucleus has lower atomic number
• Beta decay


  1. Neutron in nucleus decays to proton, electron and antineutrino

  2. Atomic number increases by 1
• Annihilation of particle-antiparticle pair produces 2 photons
• Photon energy


  Equals 2mc^2 (rest energy of particles)
• Photon energy


  Equals hf (Planck's constant times frequency)
• Pair production


  High energy photon converts to particle-antiparticle pair
• Electron energy levels


  Discrete, with ground state (n=1) and higher excited states (n=2, 3, etc.)